Alkylphosphonothioates



United States Patent 3,145,140 ALKYLPHOSPHONOTHIOATES John P. Chupp, Kirlrwood, Md, and Peter E. Newallis, Morris Plains, NJ, assignors to Monsanto Company, a corporation of Delaware No Drawing. Filed Dec. 3, 1962, Ser. No. 241,484 13 Claims. (Cl. 167-30) This invention relates to novel alkylphosphonothioates and additionally relates to insecticidal compositions containing the alkylphosphonothioates of this invention as an active ingredient.

The alkylphosphonothioates of this invention can be represented by the formula wherein R is a mono-halogen substituted phenyl radical of the group consisting of 2-halophenyl and .3-halophenyl, the halogen substituent having an atomic weight in the range of 35 to 80, and wherein R is a lower alkyl radical (e.g. methyl, ethyl, propyl, butyl, amyl, and the various isomeric forms thereof containing up to carbon atoms). In general R will be methyl or ethyl but usually methyl.

As illustrative of this invention but not limitative thereof is the following:

Example I To a suitable reaction vessel equipped with a thermometer, agitator and reflux condenser is charged approximately 132 parts by weight of benzene, approximately 6.4 parts by weight (substantially 0.05 mole) of 2-chlorophenol, approximately 6.1 parts by weight (substantially 0.06 mole) of triethylamine, and approximately 10.8 parts by weight (substantially 0.05 mole) of O-(4-nitrophenyl) methylphosphonochloridothionate. While agitating the mixture is heated up to the reflux temperature and then refluxed for 5 hours. The reaction mass is then cooled to room temperature and then quenched with water. The organic layer is separated and washed first with aqueous 3% sodium carbonate and then with water. The sowashed solution is then stripped of volatiles under vacuum. The residue, a solid melting at 84-66 C., is O-(.2chloro' phenyl) O-(4-nitrophenyl) methylphosphonothioate.

Example 11 Employing the procedure of Example I but replacing Z-chlorophenol with an equimolecular amount of Z-bromophenol there is obtained O-(Z-bromophenyl) O-(4-nitrophenyl) methylphosphonothioate, a solid melting at 71- 73 C,

Example Ill To a suitable reaction vessel equipped with a thermometer, agitator and reflux condenser is charged approxi mately 176 parts by weight of benzene, approximately 6.4 parts by weight (substantially 0.05 mole) of 3-chlorophenol, approximately 6.1 parts by weight (substantially 0.06 mole) of triethylamine, and approximately 10.8 parts by weight (substantially 0.05 mole) of O-(4-nitrophenyl) methylphosphonochloridothionate. While agitating the mixture is heated up to the reflux temperature and then refluxed for 5 hours. The reaction mass is then cooled to room temperature and then quenched with water. The organic layer is separated and washed first with aqueous 3% sodium carbonate and then with water. The sowashed solution is then stripped of volatiles under vacuum. The residue is O-(3-chlorophenyl) O-(4-nitrophenyl) methylphosphonothioate which melts at 75-77" C.

Example IV Employing the procedure of Example III but replacing 3-chlorophenol with an equimolecular amount of 3-bromophenol there is obtained O-(3-bromophenyl) O(4-nitrophenyl) methylphosphonothioate which is insoluble in water.

Example A Employing the procedure of Example I but replacing 2-chlorophenol with an equimolecular amount of 4-chlorophenol there is obtained O-(4-chlorophenyl) O-(4-nitrophenyl) methylphosphonothioate, a solid.

Example B Employing the procedure of Example I but replacing 2-chloropl1enol with an equimolecular amount of 2,4-dichlorophenol there is obtained 0-(2,4-dichlorophenyl) O- (4-nitrophenyl) methylphosphonothioate which melts at 845-" C.

Example C Employing the procedure of Example I but replacing 2-chlorophenol and O-(4-nitrophenyl) methylphosphonochloridothionate with equimolecular amounts of 3-chloro- 4-nitrophenol and O-phenyl methylphosphonochloridothionate there is obtained O-phenyl O-(3-chloro-4-nitrophenyl) methylphosphonothioate an oil which is insoluble in water. I

The methods by which the alkylphosphonothioates of this invention are isolated will vary slightly with the reactants employed and the product produced. Further purification by selective solvent extraction or by absorptive agents such as activated carbon or clays can precede the removal of the inert organic liquid or solvent when such is employed. Additionally in inert organic solvent can be added to and in the purification of absorptive agents. However, the product is generally satisfactory for insecticidal purposes without further purification.

It will be understood that the terms insect and insecticide are used herein in their broad common usage to include spiders, mites, ticks, and like pests which are not in the strict biological sense classed as insects. Thus the usage herein conforms to the definitions provided by Congress in Public Law 104, the Federal Insecticide, Fungicide, and Rodenticide Act of 1947, Section 2, subsection h, wherein the term insect is used to refer not only to those small invertebrate animals belonging mostly to the class Insecta, comprising sixlegged, usually winged forms, as beetles, bugs, bees, filies, and so forth, but also to other allied classes of arthropods Whose members are Wingless and usually have more than six legs, as spiders, mites, ticks, centipedes, and wood lice.

The alkylphosphonothioates of this invention are effective against a wide variety of insects and as illustrative of their activity but not limitative thereof is the following:

A rimless, 25 x 200 mm. culture tube is rinsed with acetone and is placed in a holding block. The tube is filled with 50 cc. of distilled water. Next 0.1 cc. or 0.1 gram of the compound to be evaluated is dissolved in acetone to make a 1% by weight concentrate of the compound. 0.05 ml. of this concentrate is pipetted into the culture tube containing the distilled water. The tube is then stoppered with an acetone washed rubber stopper and shaken vigorously to facilitate complete mixing. Approximately 25 early fourth instar yellow fever mosquito larvae (Aedes aegypli) are transferred to the tube with the aid of a pipette. The larvae are held in the test tube at room temperature for 24 hours at which time mortality observations are taken. This procedure is repeated at decreasing concentrations and employing the below itemized compounds the percent kill observed at a concentration of 004 part per million:

A 1% by weight concentrate is prepared by dissolving the compound to be evaluated in ml. of acetone. A 0.25 cc. tuberculin, BD Yale syringe is filled with this concentrate and placed in a microinjection apparatus. The injector lever is pressed several times to make certain no air bubbles are trapped in the needle and the needle is wiped with filter paper to remove any excess solution. The injector lever is pressed once to deliver one microliter which is applied directly to each of 12 Lima bean leaf discs 0.25 inch in diameter. Individual second instar southern armyworm larvae (Prodenia eridania) are placed on each disc and the disc encaged with a plastic cap. After 48 hours at room temperature mortality observations are made. This procedure is repeated at decreasing concentrations and employing the below itemized compound the precent kill observed at a concentration of 0.2 microgram per larva:

Percent O-(2-chlorophenyl) O-(4-nitrophenyl) methylphosphonothioate 100 O-(Z-bromophenyl) O-(4-nitrophenyl) methylphosphonothioate 100 O-(3-chlorophenyl) O-(4-nitrophenyl) methylphosphonothioate 100 O-(4-ch1orophenyl) O-(4-nitrophenyl) methylphosphonothiate 5O O-(2,4-dichlorophenyl) O-(4-nitrophenyl) methylphosphonothioate 0 O-phenyl O-(3-chloro-4-nitrophenyl) methylphosphonothiate A 1% by weight concentrate of the compound to be evaluated is prepared by dissolving the chemical in 10 ml. of acetone. A 0.25 cc. tuberculin, B-D Yale syringe is filled with the concentrate and placed in a microinjection apparatus. The injector lever is pressed several times to make certain that no air bubbles are trapped in the needle and the needle is wiped with filter paper to remove any excess solution. The injector lever is pressed once to produce one microliter which is applied directly to the ventral side of the abdomen of each of 10 plum curculio (Conotrachelus nenuphar). After application each insect is released within observation dishes and held for 24 hours at room temperature and mortality observations made at the end of that time. This procedure is repeated at decreasing concentrations and employing the below itemized compounds the percent kills observed at a concentration of of 2 micrograms per insect:

Percent O-(2-chlorophenyl) O-(4-nitrophenyl) methylphosphonothioate 100 O-(Z-bromophenyl) O-(4-nitrophenyl) methylphosphonothioate 100 O- 3-chlorophenyl) O- (4-nitrophenyl) methylphosphonothioate 100 O-(4-chlorophenyl) O-(4-nitrophenyl) methylphosphonothioate 0 O-(2,4-dichlorophenyl) O-(4-nitrophenyl) methylphosphonothioate 0 Although the phosphonothioates of this invention are useful per se in controlling a wide variety of insect pests, it is preferable that they be supplied to the pests or to the environment of the pest or pests in a dispersed form in a suitable extending agent.

In the instant specification and appended claims it is to be understood that the term dispersed is used in its widest possible sense. When it is said that the phosphonothioates of this invention are dispersed, it means that particles of the phosphonothiates of this invention may be molecular in size and held in true solution in a suitable organic solvent. It means further, that the particles may be colloidal in size and distributed throughout a liquid phase in the form of suspensions or emulsions or in the form of particles held in suspension by wetting agents. It also includes particles which are distributed in a semi-solid viscous carrier such as petrolatum or soap or other ointment base in which they may be actually dissolved in the semi-solid or held in suspension in the semi-solid with the aid of suitable Wetting or emulsifying agents. The term dispersed also means that the particles may be mixed with and distributed throughout a solid carrier providing a mixture in particulate form, e.g. pellets, granules, powders, or dusts. The term dispersed also includes mixtures which are suitable for use as aerosols including solutions, suspensions, or emulsions of the phosphonothioates of this invention in a carrier such as dichlorodifluoromethane and the like fluorochloroalkanes which boil below room temperature at atmospheric pressure.

In the instant specification and appended claims it is to be understood that the expression extending agent includes any and all of those substances in which the phosphonothioates of this invention are dispersed. It includes, therefore, the solvents of a true solution, the liquid phase of suspensions, emulsions or aerosols, the semisolid carrier of ointments and the solid phase of particulate solids, e.g. pellets, granules, dusts and powders.

The exact concentration of the phosphonothioates of this invention employed in combatting or controlling insect pests can vary considerably provided the required dosage (i.e. toxic or lethal amount) thereof is supplied to the pests or to the environment of the pests. When the extending agent is a liquid or mixture of liquids (e.g. as in solutions, suspensions, emulsions, or aerosols) the concentration of the phosphonothioate employed to supply the desired dosage generally will be in the range of 0.001 to 50 percent by weight. When the extending agent is a semi-solid or solid, the concentration of the phosphonothioate employed to supply the desired dosage generally Will be in the range of 0.1 to 25 percent by Weight. From a practical point of view, the manufacturer must supply the agriculturist with a low-cost concentrate or spray base or particulate solid base in such form that, by merely mixing with water or solid extender (e.g. powdered clay or talc) or other low-cost material available to the agriculturist at the point of use, he will have an easily prepared insecticidal spray or particulate solid. In such a concentrate composition, the phosphonothioate generally will be present in a concentration of 5 to 95 percent by weight, the residue being any one or more of the well known insecticidal adjuvants, such as the various surface active agents (eg. detergents, a soap or other emulsifying or Wetting agent), surface-active clays, solvents, diluents, carrier media, adhesives, spreading agents, humectants, and the like.

There are a large number of organic liquids which can be used for the preparation of solutions, suspensions or emulsions of the phosphonothioates of this invention. For example, isopropyl ether, acetone, methyl ethyl ketone, dioxane, cyclohexanone, carbon tetrachloride, ethylene dichloride, tetrachloroethane, hexane, heptane and like higher liquid alkanes, hydrogenated naphthalenes, solvent naptha, benzene, toluene, xylene, petroleum fractions (e.g. those boiling almost entirely under 400 F. at atmospheric pressure and having a flash point above about F, particularly kerosene), mineral oils having an unsulfonatable residue above about 80 percent and preferably above about 90 percent. In those instances wherein there may be concern about the phytotoxicity of the organic liquid extending agent a portion of same can be replaced by such low molecular weight aliphatic hydrocarbons as dipentene, diisobutylene, propylene trimer, and the like or suitable polar organic liquids such as the aliphatic ethers and the aliphatic ketones containing not more than about carbon atoms as exemplified by acetone, methyl ethyl ketone, diisobutyl ketone, dioxane, isopropyl ether, and the like. In certain instances, it is advantageous to employ a mixture of organic liquids as the extending agent.

When the phosphonothioates of this invention are to be supplied to the insect pests or to the environment of the pests as aerosols, it is convenient to dissolve them in a suitable solvent and disperse the resulting solution in dichlorodifluoromethane or like chlorofluoroalkane which boils below room temperature at atmospheric pressure.

The phosphonothioates of this invention are preferably supplied to the insect pests or to the environment of the insect pests in the form of emulsions or suspensions. Emulsions or suspensions are prepared by dispersing the phosphonothioate of this invention either per se or in the form of an organic solution thereof in water with the aid of a water-soluble surfactant. The term surfactant as employed here and in the appended claims is used as in volume 11 of Schwartz, Perry and Berchs Surface Active Agents and Detergents (1958, Interscience Publishers, Inc., New York), in place of the expression emulsifying agent to connote generically the various emulsifying agents, dispersing agents, wetting agents and spreading agents that are adapted to be admixed with the active compounds of this invention in order to secure better wetting and spreading of the active ingredients in the water vehicle or carrier in which they are insoluble through lowering the surface tension of the water (see also Frear, Chemistry of Insecticides, Fungicides and Herbicides, second edition, page 280). These surfactants include the well-known capillary-active substances which may be anion-active (or anionic), cation active (or cationic), or nonionizing (or non-ionic) which are described in detail in columes I and II of Schwartz, Perry and Berchs Surface Active Agents and Detergents (1958, Interscience Publishers, Inc., New York), and also in the November 1947 issue of Chemical Industries (pages 811-824) in an article entitled Synthetic Detergents by .lohn W. McCutcheon, and also in the July, August, September and October 1952 issues of Soap and Sanitary Chemicals under the title Synthetic Detergents. The disclosures of these articles with respect to surfactants, i.e. the anion-active, cation-active and the non-ionizing capillary active substances, are incorporated in this specification by reference in order to avoid unnecessary enlargement of this specification. The preferred surfactants are the water-soluble anionic surface-active agents and the water-soluble non-ionic surface-active agents set forth in US. 2,846,398 (issued August 5, 1958). In general it is preferred that a mixture of water-soluble anionic and water-soluble non-ionic surfactants be employed.

The phosphonothioates of this invention can be dispersed by suitable methods (e.g. tumbling or grinding) in solid extending agents either of organic or inorganic nature and supplied to the insect pests environment in particulate form. Such solid materials include for eX-' ample, tricalcium phosphate, calcium carbonate, kaolin, bole, kieselguhr, talc, bentonite, fullers earth, pyrophillite, diatomaceous earth, calcined magnesia, volcanic ash, sulfur and the like inorganic solid materials, and include, for example, such materials of organic nature as powdered cork, powdered wood, and powdered Walnut shells. The preferred solid carriers are the adsorbent clays, e.g. bentonite. These mixtures can be used for insecticidal purposes in the dry form, or by addition of water-soluble surfactants or wetting agents the dry particulate solids can be rendered wettable by water so as to obtain stable aqueous dispersions or suspensions suitable for use as sprays.

For special purposes the phosphonothioates of this invention can be dispersed in a semi-solid extending agent such as petrolatum or soap (e.g. sodium stearate or oleate or palmitate or mixtures thereof) with or without the aid of solubility promotors and/ or surfactants or dispersing agents.

In all of the forms described above the dispersions can be provided ready for use in combatting insect pests or they can be provided in a concentrated. form suitable for mixing with or dispersing in other extending agents. As illustrative of a particularly useful concentrate is an intimate mixture of phosphonothioate of this invention with a water-soluble surfactant which lowers the surface tension of water in the weight proportions of 0.1 to 15 parts of surfactant with sufiicient of the phosphonothioate of this invention to make 100 parts by weight. Such a concentrate is particularly adapted to be made into a spray for combatting various forms of insect pests by the addition of water thereto. As illustrative of such a concentrate is an intimate mixture of parts by weight of O-(Z-chlorophenyl) O-(4-nitrophenyl) methylphosphonothioate and 5 parts by weight of a water-soluble non-ionic surfactant such as the polyoxyethylene derivative of sorbitan monolaurate.

Another useful concentrate adapted to be made into a spray for combatting a variety of insect pests is a solution (preferably as concentrated as possible) of a phosphonothioate of this invention in an organic solvent therefor. The said liquid concentrate preferably contains dissolved therein a minor amount (e.g. 0.5 to 10 percent by weight of the weight of the new insecticidal agent) of a surfactant (or emulsifying agent), which surfactant is also water-soluble. As illustrative of such a concentrate is a solution of O-(3-chlorophenyl O-(4-nitrophenyl) methylphosphonothioate in benzene which solution contains dissolved therein a Water-soluble polyoxyethylene glycol non-ionic surfactant and a water-soluble alkylaryl sulfonate anionic surfactant.

Of the surfactants aforementioned in preparing the various emulsifiable, wettable or dispersible compositions or concentrates of this invention, the anionic and nonionic surfactants are preferred. Of the anionic surfactants, the particularly preferred are the well known watersoluble alkali metal alkylaryl sulfonates as exemplified by sodium decylbenzene sulfonate and sodium dodecylben- Zene sulfonate. Of the non-ionic surfactants, the particularly preferred are the water-soluble polyoxyethylene derivative of alkylphenols (particularly isooctylphenol) and the Water-soluble polyoxyethylene derivatives of the mono-higher fatty acid esters of hexitol anhydrides (e.g. sorbitan). These materials in general contain 15 to 30 moles of ethylene oxide per mole of the hexitol anhydride or the alkylphenol.

In all of the various dispersions described hereinbefore for insecticidal purposes, the active ingredient can be one or more of the compounds of this invention. The compounds of this invention can also be advantageously employed in combination with other pesticides, including for example, nematocides, bactericides, and herbicides. In this manner it is possible to obtain mixtures which are effective against a Wide variety of pests and other forms of noxious life.

In controlling or combatting insect pests the phosphonothioates of this invention either per se or compositions comprising same are supplied to the insect pests or to their environment in a lethal or toxic amount. This can be done by dispersing the new insecticidal agent or insecticidal composition comprising same in, on or over an infested environment or in, on or over an environment the insect pests frequent, e.g. agricultural soil or other growth media or other media infested with insect pests or attractable to the pests for habitational or sustenance or propagational purposes, in any conventional fashion which permits contact between the insect pests and the phosphonothioates of this invention. Such dispersing can be brought about by applying sprays or particulate solid compositions to a surface infested with the insect pests or attractable to the pests, as for example, the surface of an agricultural soil or other media such as the above ground surface of plants by any of the convention methods, e.g. power dusters, boom and hand sprayers, and spray dusters. Also for sub-surface application such dispersing can be carried out by simply mixing the new insecticidal agent per se or insecticidal spray or particulate solid compositions comprising same with the infested environment or with the environment the insect pests frequent, or by employing a liquid carrier for the new insecticidal agent to accomplish subsurface penetration and impregnation therein.

While this invention has been described with respect to certain embodiments, it is to be understood that it is not so limited and that variations and modifications thereof obvious to those skilled in the art can be made without departing from the spirit and scope thereof.

The embodiments of the invention, in which an exclusive property or privilege is claimed, are defined as follows:

1. An O-(4-nitrophenyl) alkylphosphonothioate of the formula wherein R is lower alkyl and wherein R is a monohalogen substituted phenyl radical selected from the group consisting of 2-ha1ophenyl and 3-halophenyl, the halogen substituent having an atomic weight in the range of 35 to 80. 2. O-(4-nitrophenyl) O-(2-chlorophenyl) methylphosphonothioate.

3. O-(4-nitrophenyl) O-(S-chlorophenyl) methylphosphonothioate.

4. O-(4-nitrophenyl) O-(Z-bromophenyl) methylphosphonothioate.

. 5. O-(4-nitrophenyl) O-(3-bromophenyl) methylphosphonothioate.

6. An insecticidal composition comprising a compound of claim 1 dispersed in an extending agent.

7. An insecticidal composition comprising a compound of claim 1 dispersed in an extending agent selected from the group consisting of solid and semi-solid extending agents, the composition containing 0.1 to 25 percent by weight of said compound of claim 1.

8. An insecticidal composition comprising a compound of claim 1 dispersed in a liquid extending agent, the composition containing 0.001 to percent by weight of said compound of claim 1.

9. An insecticidal concentrate comprising a compound of claim 1 and an insecticidal adjuvant, said concentrate containing from 5 to percent by weight of the compound of claim 1.

10. An insecticidal concentrate comprising a compound of claim 1 dispersed in an organic solvent therefor and having dissolved therein a minor amount of a surfactant, said concentrate forming an emulsion with water upon agitation therewith.

11. An insecticidal concentrate adapted to be made into a sprayable composition by the addition of water comprising a compound of claim 1 in admixture with a water-soluble surfactant in the weight proportion of 0.1 to 15 parts of surfactant and sufficient of said compound of claim 1 to make parts by weight.

12. The method of controlling insects which comprises contacting the insects with a toxic amount of a compound of claim 1.

13. The method for protection of plants against insect attack which comprises applying to the plant an insectiicdal amount of a compound of claim 1.

Toy Ian. 26, 1960 Dunn Jan. 10, 1961 

1. AN O-(4-NITROPHENYL) ALKYLPHOSPHONOTHIOATE OF THE FORMULA
 12. THE METHOD OF CONTROLLING INSECTS WHICH COMPRISES CONTACTING THE INSECTS WITH A TOXIC AMOUNT OF A COMPOUND OF CLAIM
 1. 